Illuminating measuring instrument



Maya5, 1959 T. A. GREEN ET AL 2,885,536

ILLUMINATING MEASURING INSTRUMENT Original Filed July 22;, 1950 mes F9530 L48 R E20 I l V: l5

I :IO I I I c 5 I I l= 4 I INVENTORS THOMAS A. GREEN, HARVARD H. GORRIE,

TREVOR FIN'K United States Patent ILLUMINATING MEASURING INSTRUMENT Thomas A. Green, Willoughby, Harvard H. Gorrie, Cleveland Heights, Jack F. Shannon, Euclid, and Trevor Fink, University Heights, Ohio, assignors to Bailey Meter Company, a corporation of Delaware Original application July 28, 1950, Serial No. 176,382. Divided and this application June 10, 1954, Serial No. 435,883

2 Claims. (Cl. 240-21) Our invention relates to measuring instruments and particularly to indicating pressure gages of the vertical edgewise class.

The general shape is of a relatively thin rectangle with one end or edge of the rectangle fitted for visually observing the indication of measurement by having one or more pointers arranged to move along a vertically located scale path. Preferably the unit is mounted with the indicative scale substantially flush with a panel board, the majority of the unit projecting behind the panel.

Our unitary construction is not, however, restricted to vertical edgewise panel mounting. One widely accepted usage is for table mounting on bench or console type control panels where the scale edge of the unit is horizontal or at a slight inclination with the horizontal and with most of the unit projecting beneath the bench or console top. Furthermore, the unitary enclosed construction allows theganging-up or stacking of numerous units with the indicative scales parallel or end-to-end. On the other hand, the unit may be incorporated in an assembly of metering or control apparatus to advantage.

While we have chosen to designate our invention as related to pressure gages, we so-name a general class without meaning to restrict the usefulness of the invention in the measurement of other variable quantities, qualities, conditions, positions, or the like.

The principal object of our invention is to provide an indicating gage of unitary construction adapted for universal mounting or arrangement in multiple or with other apparatus and having an arcuate scale, a reflector plate arranged in particular angular relation to the scale, and a detachable source of illumination arranged to radiate onto the scale and the reflector plate.

A further object resides in providing an indicating gage having the scale, reflector, and illuminating source indicated adapted to the ready ganging, or grouping of a plurality of such instruments.

Another object is to provide an indicating receiver of substantially universal adaptability to different forms and having illuminating means including a light gathering reflector and a detachable source of illumination.

Still other objects will be apparent from a study of the drawings, the description thereof, and of our claims.

In the drawings:

Fig. 1 is a sectional elevation of a single tube gage.

Fig. 2 is a front face view of the assembly of Fig. 1.

Fig. 3 is a view of a portion of the assembly of Fig. 1 taken along the line 33 in the direction of the arrows.

Fig. 4 is an enlarged view of that portion of Fig. l enclosed by dot-dash line and designated 4.

Fig. 5 is an exploded view of a portion of Fig. 1.

Referring now in particular to Fig. l, we show therein a side elevational view of our preferred apparatus as embodied in what is sometimes termed a vertical edgewise indicator. The housing 20 is formed as a die casting obtaining lightness, with rigidity, strength and dust tightness. The shape is in general rectangular with a flat side mounting wall 21, top wall 22, bottom wall 24 and a rear wall 23. The near side is normally covered by a removable side plate 25 (Fig. 5) which may be held to the housing 20 by screws threadable into holes 26. For purposes of illustration the housing 20 of Fig. 1 has been sectioned slightly below the ledge (Fig. 5) which provides a resting place for the cover 25.

The housing 20 has no fixed front wall (to the right as viewed in Fig. 1) but the opening is desirably closed by a molded transparent window 27 which may be of glass or a clear plastic. The latter is preferred as less susceptible to breakage through handling, vibration or shock. The window 27 is formed with a long radius protrudance to the right (Fig. 1) beyond the limits of housing walls 21, 22, 24. The two sides 28 and 29 of window 27 extend rearwardly to join the forward edges of side wall 21 and of cover 25. Along the top a rearward projection 30, and along the bottom a similar projection 31, enter the confines of the housing as shown. The projection 31 is provided with a hole 32 which may be adapted to receive a spring end 33 as shown in Fig. 1 or in the dotted position of Fig. 4. In similar manner the upper projection 30 is provided with a hole receiving a more rigid spring end 34. Figs. 1 and 2 show the window 27 in its assembled location with projections 30 and 31 receiving the ends 33, 34 and thus holding the window tightly closing the end opening formed by the housing 20 and cover 25.

Provision is made for easy assembly as well as for ready removal of the window portion 27 for inspection and cleaning of the scale, pointer, etc. Figs. 1 and 2 show the window in its assembled position. Fig. 4 is an enlarged detail of a lower right-hand portion of Fig. 1 illustrating the operation to be performed for removing or inserting window 27. 7

Referring now particularly to Fig. 4 the dot-dash outline to the left shows the window structure in the same assembled location as in Fig. 1. If it is desired to remove the window structure then a lifting screw 35 may be threaded upwardly through the tapped hole 36 of the leaf spring 37 until the upper end of-screw 35 engages the fixed lower end of rivet 38. Continued threading of screw 35 into hole 36 flexes the right-hand end of spring 37 (around its pivot 39) downwardly thus withdrawing the pin end 33 from the hole 32 to a position shown in solid line in Fig. 4.

Such withdrawal of the pin 33 from the hole 32 allows an operator, through grasping the lower portion of window 27, to move the lowermost projection 31 outwardly from the wall 24 until the pin 34 no longer engages the upper projection 30 and the window 27 is completely removed. It may be reinserted through a reverse operation of first engaging the hole in upper projection 30 with the pin 34 and then sliding the lower portion of the window inwardly until it completely closes the end cavity of the assembly. Thereafter a backing off of the screw 35 allows pin 33 to enter the hole 32 and lock the window in place. The screw 35 may be left partially inserted in the cavity 36 or may be removed as is shown in Fig. 1.

Referring again to Fig. 4 it will be seen that the rivet 38 serves additionally to hold the scale plate assembly by engaging a projection 40 thereof. The scale plate 41 itself is curved to an arc corresponding to the travel of the indicating pointer and may be the same or slightly different than the outward surface are of the window 27. It is only essential to maintain sufiicient clearance between the pointer, scale plate 41 and inner surface of window 27, at the mid-travel position of the pointer.

The lowermost end of the scale plate 41 receives a rivet 42 holding to it a spring clip 43 efiectively spacing the scale plate 41 from the inner lower edge of the Patented May 5, 1959 3 window housing. i iFtlTe-upper end of thescale plate 41 a similar spring clip -44 is provided as well as a projection 45 of the scale plate (similar to the projection 40). The pin clip 34 as well as the projection 45 are held by a =rivet- 46 to the' top wall The forwardly arched scale plate 41 is recessed along its edges as at 47, -48providing clearanc'e paths forrnovable pointers. Centered --along the arc "face of the scale plate 41is a raisedscale'portion'49 upon which are engraved or painted the scale graduations. Preferably the side portions 50, 51 containinforrnation, relative to the scale graduations, of Service--which may be flow, pressure,-orthe like; and of numerals 0, -10, 20, etc. relating to the Service" and to the scale graduations.

Preferably the pointer end 52 (Fig. 2) travels over the depressed'surface '50 (or 51) with clearance thereover and with its indicating end adjacent to graduations on the elevated-portion '49. As viewed in Fig. 1 it will be observed that the pointer 52 does not extend beyond tliearc of the "surface 49 and does not in any respect overlap the graduations or produce parallax in reading the gage.

In the present embodiment, illumination of the unit is "accomplished by a recessed light-bulb 53 mounted in top wall 22 behind the window 27 and scale plate 41. A light reflectingsurface or wall 54 may be formed by the bottom wall of a U-shaped member held in position by 'the rivet 42 and having side walls spaced from the side wall 21and the inside of cover25 to allow pointer travel. This-substantiallyprevents light'frorn the source 53 enteringthe housingsurrounding shield 54 and minimizing eye viewing of working parts of the instrument behind theshield-54 through-the slots 47, 48. Normally the scale plate 41 may he of some translucent plastic or similar material upon which the graduations and other i'ndicia are painted or engraved so that they will stand outin contrast to the lighted scale plate itself whe'nthe latter is illuminated by the source 53 and reflection from the surface 54.

The light source 53 maybe held in a convenient s'ocket assembly 55 having terminals 56 and the assembly is removably mounted in a clip "57 (Fig. '5) having'on'e or more locking prongs 58 engageable with the inner "surface of a hole 59 formed-in the upper wall 22 of the housing20. The assembly is shown in Fig. 1 inits normal operation position wherein the prongs 58 are in engagement and a spring button 60 carried by'the clip 57 is thus expanded through a hole 61 in the top of wall 22.

From the assembledposition (Fig. l) the assembly 53, 55, 56, 58, 60 cannot be loosened or pulled fromthe unit, in any direction except that shown by the arrow X of Fig. 5. In other words,-anystrain on 55 or 56, as by wires or conduit, toward the observer of Fig. 1, or away fromthe observer, 'ortoward the left, will not'cause a pull-out of the assembly due to the gripping of wedge prongs 58; and those are the normal directions of undesired strains upon 55, i.e., away from the back of a panel through which the window 27 projects. Desired removal is, however, readily accomplished by pivoting the assembly toward the rear of the panel in the direction of the arrowX (Fig. 5).

The operative'or active element of our improved indicator is illustrated in Fig. l as a Bourdon tube 65 having one end permanently fastened to a base casting or forging 66which is in turn held by screws '67'to the back 21 of the housing 20. Allof the contents-of the housing are supported "relative to the side'plate 21 'so that the oover 2 5 may-readily be "removed without disturbing any of theactiveelementswhih may continue in operation.

Thehiteriar ofthe *Bottrdontube 65 communicates witha passage'68 and thelower wall24ispr'ovided with a clearance opening 69 to allow -pipe con'nectionto'the passage 68. V I g The free end of the Bourdon tube 65 is connected through anaement resonating-fink 71 and U-sha'ped 4 member 72 to angularly position the shaft 73. The shaft 73 is pivotally supported by -an--assembl-y-held together by screws 81. One of the plates 80 has an extension 82 through which screws 83 pass into base 66 providing a rigid mounting for the shaft 73. Carried by the shaft 73, in addition to the U shaped member 72, is an enlarged hub 73A and a-toothed disc 79. Angularmotion of the shaft -73, hy the Bou'rdon tube '65, through the agency of elements '71and 72, angularly move's the elements 73A and 79.

The pointer arm 74 has a weighted end portion 75 and the pointer arm assembly "has a hole clearing the shaft 73. In Fig. :3 the hpointer arm '74- a'nd weight 75 are at the right of 'tootheddisc7-9 and carry a br'ac'ket 76 which spans the disc 79 to encircle the hub 73A-on the left-hand side of disc 79. The bracket 76 is fastened to the pointer arm'74by a rivet' 76A.

Carried by the bracket 76, and engaging with the toothed disc 79 is a worm 78extending i'n a'pl'anelparallelto pointer arm 74. Turning-oftheworm 78 in'the the teeth of disc 79 angularly moves the assembly 52, 74,

75, 76, 76A, and 78 around the disc 79 and "shaft '73. This provides a zero adjustmentfo'r the pointer "52 relative to the scale graduations 49 without movement'of the shaft 73 or any of the elements *whih "coo erate to angularly position-the shaft under the dictates "of the Bour'don tube 65. The bracket 76, between hub73Aand rivet 76A, locks worm 78 snugly into engagement with teeth 79 thereby eliminating 'error 'due to clearances '-'required for manufacture and operation.

V Carried also by the shaft 73 is'one end of ahair"s'pring 85, the other end being adjustably clamped as at' 86 'to an extension of a plate '80, for takin'g'up -lost motion of the assembly.

As previously mentioned the Bourdon tube "angularly positions the shaft 73 thrbugh'the agency of "an element '70, connecting link '71 and U-shaped member 72.

The member 72 is "fastened at one "end to the shaft 7'3 and at its other end carries an "extension 'havi'ng'a plurality of range holes through whichwe may selectively p'ass one end of the link 71. A 's'crew'91 is threaded through an arm of the member 72 'and has its end bearing against the other arm ofthe 'mernber in a hole or bearing dimple. Adjustment of the screw'91 serves to position the holes relative to the pivot '73 and to thus vary the distance relative to the length of the pointer arm. Thusthe "selective holes and the ad justing screw 91 provide a"'meansforvarying the range of pressure which "must a'ct upon the Bourdon'tube65 to accomplish a predetermined travel of the "p'ointer52 over the scale 49. Initial adjustment of 'screw91 stresses the U member 72 toward an openposition so that the screw is 'always tightly effective across thearms o fthe U.

Both the zero adjusting screw 78 and the range adjusting screw 91 are accessible "through an opening 92 (Fig. 1) normally'covered by a clip 93 held-inlplace'by the spring plug 94.

At this point we may observe that the system being described is equally applicable to the measurement an'd indication of either.positivepressures or of negativejpressures. In the latter case it may be desirable to turn the unit upside down and reverse the scale which would then he graduated from -zero to whatever negative pressure was desired for total movement of the pointer 52.

After the pointer arm assembly is statically and dynamically balanced it is mounted in the unit, and, with the unit in a verticalposition (Figs. 1 and Z) thepointer will remain in any givennposition. -'Ihehair-spring SS is then given an initial bias such that the pointer 52 rests at its lowermost travel position (opposite zero) which is actually about one p.s.i. above zero pressure (atmospheric) within the Bourdon tube. Under this bias condition thehair-spring is fastened as at 86 and the link 71 s'houldjust fit the-distance between holes 9 5- 90.

The Bourdon tube elements 65, 70 are not balanced and are subject to vibration, harmonics, etc. On the other hand the pointer assembly is balanced. It is this balance, plus the loop link 71, which prevents undesired movements of the Bourdon tube end from being transmitted to, and observed at, the pointer 52. The flexing of the loop 71 allows the Bourdon tube which is unbalanced to move or vibrate without affecting the pointer which is balanced.

This application constitutes a division of our copending application SN 176,382 filed July 28, 1950 and now abandoned.

What we claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a measuring instrument for indicating the value of a variable, the combination comprising a thin rectangular shaped housing having one end upon which the observation is made, a curved transparent scale plate having a relatively long radius of curvature attached to said one end of said housing to present a narrow convex surface to the observer, said curved scale plate defining an arc chord connecting the ends thereof, a member having a narrow flat reflecting wall positioned in said housing behind said scale plate and forming an acute angle with the arc chord of said scale plate, said reflecting wall having one end attached to one end of said scale plate and the other end thereof terminating in spaced relationship with the other end of said scale plate, and a source of illumination attached to a wall of said housing adjacent said other ends of said scale plate and said reflecting wall for directing radiation into the space between said scale plate and said reflecting Wall, said source being positioned with respect to said scale plate and said reflecting wall to eifect direct impingement of its radiation on both the rear surface of said scale plate and on said reflecting wall to thereby uniformly illuminate said scale plate over its arcuate length by the combination of direct radiation from said source and reflection from said reflecting wall.

2. The combination of claim 1 wherein said member is U-shaped having a pair of side walls extending from said reflecting Wall toward and having their outer edges in contact with the rear curved surface of said scale plate for substantially its entire length, said side walls being effective to confine the radiation from said source to the space between said scale plate and said reflecting wall.

References Cited in the file of this patent UNITED STATES PATENTS 1,631,997 Benjamin June 14, 1927 1,743,401 Schlaich Jan. 14, 1930 1,803,119 Lucas Apr. 28, 1931 1,851,688 Warren Mar. 29, 1932 1,939,774 Hofferbert Dec. 19, 1933 2,009,209 Scantlebury July 23, 1935 2,106,152 Mattes Jan. 18, 1938 2,268,268 Simon Dec. 30, 1941 2,426,713 Simpson Sept. 2, 1947 2,561,691 Eckert et al. July 24, 1951 2,591,571 Marino Apr. 1, 1952 2,723,342 Neugass Nov. 8, 1955 FOREIGN PATENTS 355,029 Great Britain Aug. 20, 1931 

